Refsum's disease: a peroxisomal disorder affecting phytanic acid alpha-oxidation

Area of Science:

• Biochemistry
• Genetics
• Neurology

Background:

• Refsum's disease (hereditary motor sensory neuropathy type IV) is an autosomal recessive disorder characterized by phytanic acid accumulation.
• Clinical features include retinitis pigmentosa, sensory neuropathy, ataxia, and neurological deficits.
• Phytanic acid metabolism involves key enzymes localized in peroxisomes.

Purpose of the Study:

• To review the clinical, biochemical, and metabolic features of Refsum's disease.
• To elucidate the role of phytanoyl-CoA 2-hydroxylase (PAHX) and other enzymes in phytanic acid metabolism.
• To explore potential links between alpha-oxidation pathways and isoprenoid lipid metabolism.

Main Methods:

• Review of existing literature on Refsum's disease.
• Analysis of genetic and biochemical pathways involved in phytanic acid metabolism.
• Examination of enzyme functions, including PAHX, and their genetic basis.

Main Results:

• Cloning of key enzymes phytanoyl-CoA 2-hydroxylase (PAHX) and 2-hydroxyphytanoyl-CoA lyase, localized in peroxisomes.
• PAHX mutations explain some, but not all, Refsum's disease cases.
• Atypical cases may involve rhizomelic chondrodysplasia punctata or alpha-methylacyl-CoA racemase deficiency.

Conclusions:

• Understanding phytanic acid metabolism and PAHX function is crucial for Refsum's disease diagnosis and treatment.
• Further research into isoprenoid lipid metabolism may reveal novel therapeutic targets.
• The review highlights the complex interplay between genetic defects and metabolic dysregulation in Refsum's disease.